feat: ffprobe + TMDb scrape + HLS transcode + history/favourites/playlists

Backend
  - service/ffprobe.go: thin ffprobe wrapper, parses duration / resolution /
    codecs into a typed ProbeResult. 30s per-file timeout.
  - service/tmdb.go: minimal TMDb provider (search/movie). Disabled when no
    api key; supports tmdb_api_proxy / tmdb_image_proxy overrides for users
    behind a firewall.
  - service/scraper.go: filename cleaner (handles bracketed tags, scene
    noise tokens, year extraction), per-row + per-library enrichment with a
    4 RPS throttle and WS hub progress events. Unit-tested.
  - service/scanner.go: now invokes ffprobe per file and kicks the TMDb
    scraper in the background once a library scan finishes.
  - service/transcoder.go: per-media ffmpeg HLS job manager; outputs
    index.m3u8 + seg_NNNNN.ts under cache/hls/<id>; cancels jobs on
    shutdown; publishes 'transcode' WS events.
  - service/stream.go: serves HLS playlist (with 30s wait-for-ready) and
    .ts segments with path-traversal protection. Adds Probe() helper used
    by the admin 'reprobe' button.
  - service/image_proxy.go: cached, host-allow-listed reverse proxy for
    TMDb / Bangumi / Douban / Fanart / TheTVDB images so the SPA never
    hits a CORS or GFW issue.
  - service/playback.go: history upsert, favourites toggle, playlist CRUD
    + ordered items. RecentHistory joins with model.Media in one extra
    query so the home page can render a 'Continue Watching' row.
  - handler/streaming.go + handler/playback.go: REST endpoints for HLS,
    image proxy, scrape (one + library), reprobe, history, favourites,
    playlists.
  - handler/handler.go: registers /api/hls/:id/{index.m3u8,:seg}, /api/img,
    /api/history, /api/favourites/:id, /api/playlists/* with proper
    auth/admin guards.

Frontend
  - api/client.ts: imageURL() helper; hlsURL() endpoint; reuses the JWT in
    a query parameter for <video src> and <img src>.
  - api/playback.ts: typed helpers for history, favourites, playlists.
  - components/MediaCard.tsx: optional 'progress' prop renders a thin
    bottom progress bar, used by the new Continue Watching row.
  - pages/HomePage.tsx: two rows (Continue Watching + Recently Added);
    falls back to the empty-state hint when both are empty.
  - pages/PlayerPage.tsx: hls.js (lazy-imported) with auto-fallback to
    direct play; ?mode=hls|direct query toggle; resume position written
    every 10s while playing.
  - pages/MediaDetailPage.tsx: heart toggle + admin 'rescrape' / 'reprobe'
    buttons + dedicated 'HLS 转码播放' CTA.
  - pages/FavouritesPage.tsx, PlaylistsPage.tsx, PlaylistDetailPage.tsx:
    new screens.
  - components/Layout.tsx + App.tsx: sidebar links for Favourites and
    Playlists; routes are now lazily code-split via React.lazy + Suspense
    so the initial bundle stays at ~243 KB / 82 KB gzipped (hls.js is
    fetched only on first HLS playback).

Verified: go build, go vet, go test (incl. CleanQuery cases) all pass;
frontend tsc -b && vite build emits 9 route chunks plus a deferred hls
chunk.

web/src/pages/PlaylistsPage.tsx

@@ -0,0 +1,91 @@
+import { FormEvent, useEffect, useState } from 'react'
+import { Link } from 'react-router-dom'
+import { ListPlus, Trash2 } from 'lucide-react'
+import toast from 'react-hot-toast'
+
+import { playbackAPI } from '../api/playback'
+import type { Playlist } from '../types'
+
+// Landing page for playlists. Lists every playlist owned by the current
+// user and lets them create / delete one.
+export function PlaylistsPage() {
+  const [items, setItems] = useState<Playlist[]>([])
+  const [name, setName] = useState('')
+  const [loading, setLoading] = useState(true)
+
+  const refresh = () =>
+    playbackAPI
+      .listPlaylists()
+      .then(setItems)
+      .finally(() => setLoading(false))
+
+  useEffect(() => {
+    refresh().catch(() => undefined)
+  }, [])
+
+  const onCreate = async (e: FormEvent) => {
+    e.preventDefault()
+    try {
+      await playbackAPI.createPlaylist(name)
+      toast.success('已创建')
+      setName('')
+      await refresh()
+    } catch {
+      toast.error('创建失败')
+    }
+  }
+
+  return (
+    <div className="space-y-6">
+      <h1 className="font-display text-3xl font-bold text-white">播放列表</h1>
+
+      <form onSubmit={onCreate} className="glass-panel grid gap-3 md:grid-cols-[1fr_auto]">
+        <input
+          required
+          className="input-base"
+          placeholder="新播放列表名称"
+          value={name}
+          onChange={(e) => setName(e.target.value)}
+        />
+        <button type="submit" className="neon-button">
+          <ListPlus size={16} /> 新建
+        </button>
+      </form>
+
+      {loading && <p className="text-slate-500">加载中…</p>}
+      {!loading && items.length === 0 && <p className="text-slate-400">还没有任何播放列表。</p>}
+
+      <div className="grid gap-3 md:grid-cols-2 lg:grid-cols-3">
+        {items.map((p) => (
+          <div
+            key={p.id}
+            className="glass-panel flex items-center justify-between !p-4"
+          >
+            <Link
+              to={`/playlist/${p.id}`}
+              className="font-medium text-white transition hover:text-primary-400"
+            >
+              {p.name}
+              {p.is_public && (
+                <span className="ml-2 rounded border border-primary-400/40 px-1.5 py-0.5 text-xs text-primary-400">
+                  public
+                </span>
+              )}
+            </Link>
+            <button
+              onClick={async () => {
+                if (!confirm(`删除「${p.name}」?`)) return
+                await playbackAPI.deletePlaylist(p.id)
+                toast.success('已删除')
+                await refresh()
+              }}
+              className="rounded border border-red-400/40 px-2 py-1 text-xs text-red-400 hover:bg-red-400/10"
+            >
+              <Trash2 size={12} />
+            </button>
+          </div>
+        ))}
+      </div>
+    </div>
+  )
+}